Why messages are in the SMTP Outbound folder

SUMMARY

The SMTP outbound queue has messages with the status
of Unsent.

DETAIL

Messages with the status of Unsent are messages
waiting to be sent by the SMTP service. They would include any delayed emails,
as well as ones that have not yet been sent. The Retry column will indicate the
number of times the message has been retried, and the Last Error column an
indication of why the message failed to be sent. Double clicking a message in
the queue will show more details about the message. The delay notification sent
to the original sender of the email will contain more details of why the message
cannot be sent and you can also view the SMTP log details for the message by
right clicking it in the queue and selecting View Send History from the popup
menu. Lastly, the message tracking utility can also be used, if you need to
track the message from the inbound through to the outbound over multiple
days.